This is a special group. I -- Michelle Franzen in New York the driver that caused the accident that injured comedian Tracy Morgan. And killed his writing partner was in court. Just a short time ago truck driver Kevin roper. Is charged with one count of death by auto and four counts of assault by auto. Right now I want to bring in ABC's -- -- ski in New York for more -- and give us an idea what exactly happened in court. It was a very brief appearance Michelle for Kevin -- the 35 year old Wal-Mart truck driver from Jonesboro Georgia. His lawyer entered a not guilty plea on his behalf roper didn't say anything and he was out on bail 50000 dollars which -- posted earlier. And now the prosecution begins and even though he's pleading not guilty. The defense attorneys going to have to show that the there was something else that. Cause the death of Jamie Mac as he's known on the on the comedy circuit James McNair and -- Tracy Morgan and a couple of others Tracy Morgan by the way remains in critical condition. Give us an idea what prosecutors are alleging that -- criminal in this case driving while sleep deprived. Events of the broad allegation is that Kevin roper had not slept in more than 24 hours immediately prior to the crash. And that violates federal law that says you can only drive eleven hours in a fourteen hour work day. If you are a long haul truck driver there's also a similar statute in New Jersey itself that that that 24 hour period would violate. Now defense attorneys have not exactly said. How they dispute that prosecutors said -- have not said how they arrived at that conclusion. But there have been social media accounts attributed to roper that we haven't been able to confirm. Where -- -- denials and all of this is still. A lot to sort out we're anxious to hear how prosecutors arrived at the conclusion that roper did not. The sleep for the 24 hours immediately prior to the crash and and we'd like to know whether it was. Actual falling asleep that that caused him to to -- caused the crash or whether there was some other kind of factor. Police have long suspected ever since this accident last Saturday morning at about 1 I -- on the New Jersey Turnpike. That roper was either -- Fell asleep outright or somehow -- in -- -- because he was going far too fast for the slow traffic ahead of him and they say. He only reacted at the last moment to try and avoid the collision. And of course roper was driving for the company Wal-Mart Wal-Mart also issuing a statement give us an idea of what we've heard from Wal-Mart. And could the company also be held responsible. -- Wal-Mart says it will take responsibility but it also disputes the notion that if in fact roper was up for 24 hours as prosecutors say that he was working. That time so they're -- they're saying that he was with the in the federal law when it comes to his working hours which would again would be eleven hours driving in a fourteen hour work -- Wal-Mart says Kevin roper had. Behaved accordingly. And so we don't know what else he may have been doing in a 24 hour period if he was in fact up. Prosecutors have not set. And give us an idea Aaron -- Tracy Morgan is recovering still in the hospital. Very much -- -- hospital critical but stable is how his publicist puts it and -- that for the first time we have been given an indication that he is going to make it his publicist says that he expects a recovery but one that's going to be arduous and his family has been by his side the whole time. We don't know the full extent of his injuries his publicist has said that he had a broken leg and -- had surgery to fix that and a few other injuries consistent with a rollover accident but. One wonders if perhaps there there isn't something yet more severe going on. But now critical but stable certainly good news along with two others who remain hospitalized and state prosecutors of course bringing these charges which -- criminal could James McNair -- family the person killed in this accident. Also bring civil charges against -- Oh it's certainly possible for wrongful death -- I think the criminal prosecution would take precedence that we haven't heard from. James McNair Stanley as to whether they pursue that he lives in Peekskill new York and was apparently well known around town. I -- a bunch odd jobs in addition to his work as a comedy writer for Tracy Morgan. And -- the group of them were traveling in a limo -- a Mercedes sprinter. On the way back from Delaware early Saturday morning they had performed at a hotel and casino in Delaware we're headed back to New York so they could fly out for a show on Saturday night. In North Carolina -- that show of course was canceled and and Tracy Morgan and others were airlifted from the scene of the accident. But an hour outside of New York City on the northbound lanes of the New Jersey Turnpike airlifted to Robert Wood Johnson hospital where they remain. And as you mentioned -- made bail a short time ago what happens next in this case. Well he'll he'll be back in court and and he certify that the judge that he would return for all of his estates he had been free on bail. He had turned himself in shortly after the charges were announced that he came to court -- white button down shirt and dark slacks no. You don't -- not much to it and he told the judge that he would in fact. I'd be back in court when required and his lawyer in -- not guilty plea on his behalf and we'll see if that the lawyers have -- -- -- found a little bit more on the circumstances of the crash police still haven't given a full account but they do again believe. That there was a collection of traffic that the tractor trailer roper was driving was going far too fast given that road conditions of the time in the PC conditions at the time. And it turns out that fatigue Michelle is the leading cause of crashes involving big trucks and so this has been a concern. Investigators of course still. They're still making sure that they get their investigation finished up in the meantime this court case moving forward actors can thank you so much. This has been an ABC news digital special report keep up with the story real time by downloading the ABC news -- And -- the story for exclusive updates on the go. For now I'm Michelle Franzen in New York.

This transcript has been automatically generated and may not be 100% accurate.

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